The research proposal involves the development of novel new or modified analytical atomic spectroscopic methods for either the selective measurement of extremely low concentrations of elements or isotopes of elements or the measurement of low concentrations of one or more elements with high detection power and selectivity and excellent linearity of response and precision while maintaining simplicity, versatility, and in some cases low cost of instrumentation. The research projects involve: (1) the measurement of spectral line profiles and the measurement of trace elements by means of temporal or spatial Fourier Transform Michelson interferometric systems; (2) the development of new light sources for existing fluorescence of atoms and ions in the inductively coupled plasma, ICP; the new sources include laser diodes and augmented hollow cathod lamps; also laser ablation as a means of solid sampling will be used; (3) the development and analysis of a coherent forward scattering spectrometer for multielement analysis with automatic background correction; (4) thermal evolution of stable organic and organometallic molecular species in biological samples with microwave plasma atomic emission measurement of all atomic species (C, H, S, N, O, etc.); (5) development of a novel non-dispersive atomic fluorescence spectrometric approach for the measurement of several atom types produces in flames or plasmas; (6) development of new, intense, stable electrodeless discharge lamps for atomic emission spectrometric determination of trace elements in small amounts of biological samples and their use as sources in atomic fluorescence spectrometry; (7) development of a laser microanalyzer to allow spatial measurements of small amounts of non-conducting materials, as biological tissues or trace analysis of elements in dried small volumes of solution samples, as blood; and (8) other spectroscopic studies including Doppler free atomic spectroscopy for trace levels of isotopes, a pulsed laser produced plasma in a combustion flame as a means of producing a high temperature plasma-emission system, and an optoimpedance means of detection of laser enhanced ionization in flames. In all these studies, the emphasis will be to design and evaluate by signal-to-noise ratios each system, to better understand the mechanism of response of each system, to determine analytical figures of merit of each system and to compare with conventional approaches, and to apply the optimized systems to trace species in biological materials.